In Radical Theory, Breathing Life-giving Oxygen Is Deadly

February 11, 1987|By Knight-Ridder Newspapers.

BERKELEY, CALIF. — That deep breath of fresh air may not be entirely good for you, not because it`s polluted, but because it contains oxygen.

The very act of breathing turns oxygen into rambunctious chemicals called ``oxygen radicals`` that may cause cancer and promote aging, scientists meeting at the University of California at Berkeley said last week.

``Oxygen is a dangerous friend. You can`t live without it, but you can`t continue to live with it,`` said Lester Packer, a Berkeley professor who helped organize the international meeting on oxygen radicals, where more than 100 scientists shared observations and theories about the chemicals and their effects on the body. By better understanding oxygen radicals, they hope to better understand the body`s chemistry and perhaps learn to thwart some of the radicals` hazardous effects.

``As time goes on and our methods for detecting them sharpen up, they crop up in more and more disease states, aging and cancer,`` Packer said.

Radicals are compounds whose oxygen atoms have picked up extra electrons. In this state, they react eagerly with any chemical in the vicinity. Evidence is mounting that they go careening around the body, damaging the DNA molecules that carry instructions for cells to function properly. Researchers believe this damage can lead to cancer or the slow deterioration of aging.

Radiation can trigger formation of radicals; so can certain air pollutants or cigarette smoke. But radicals also are formed, apparently in great quantities, during normal, essential body processes, such as breathing. ``What some of our evidence shows is that living is like getting irradiated,`` said biochemist Bruce Ames of the University of California at Berkeley.

Although the volatile nature of radicals makes it difficult to measure them directly, scientists have found indirect ways to determine their effects. In a recent study, Ames searched the urine of rats and humans for bits of DNA that had been damaged by radicals and then clipped out by the body`s repair mechanisms.

Based on the number of bits that he found, he concluded that human cells must sustain about 1,000 ``hits`` from radicals per day, and that rat cells sustain about 15 times as many.

Why aren`t those hits fatal? Because the body has an extraordinary ability to repair the damage and keep its cells running.

Ames said uric acid in the bloodstream may be an anti-oxidant, a chemical that blocks the harmful actions of oxygen radicals. Bilirubin, a waste product from the liver, also may be one.

Other compounds that appear to protect cells include vitamins E and C, albumin, beta carotene and several enzymes.

Richard Cutler, a biochemist at the Gerontology Research Center of the National Institute on Aging, has spent five years measuring these protective compounds in the tissues of more than 30 mammals, ranging from mice to people.